Colliding stars released radioactive molecules into space

A new study examined the radioactive remnants of an ancient star collision.
By Tyler MacDonald | Jul 31, 2018
A team of astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) and the NOEMA (Northern Extended Millimeter Array) radio telescopes to examine the remains of an explosive collision between Sun-like stars back in 1670.

The data revealed a signature of a radioactive version of aluminum, 26Al, bound with fluorine atoms, creating 26-aluminum monofluoride (26AlF). The molecule is the first of its kind to bear an unstable radioisotope outside of the Milky Way.

"The first solid detection of this kind of radioactive molecule is an important milestone in our exploration of the cool molecular universe," said Tomasz Kami?ski, an astronomer with the Harvard-Smithsonian Center for Astrophysics and lead author of the study.

The team also discovered that the two stars involved in the merger had fairly low masses, and one of them was a red giant star that weighed approximately 0.8 to 2.5 times more than the Sun.

"This first direct observation of this isotope in a stellar-like object is also important in the broader context of galactic chemical evolution," Kami?ski said. "This is the first time an active producer of the radioactive nuclide 26Al has been directly observationally identified."

As of now, theALMA and NOEMA only have the ability to detect the 26Al bound to fluorine, which means that the actual mass of 26Al might be larger. Not only that, but other merger remnants could contain much great amounts, and astronomers might have underestimated the amount of such mergers in the Milky Way.

"So this is not a closed issue and the role of mergers may be non-negligible," Kami?ski said.

The findings were published in Nature Astronomy.

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